The invention relates to the shielding of a protective lens and more particularly to the shielding of the lens of a protective face mask against abrasion, pitting, burning and the deposition of opaque material thereon.
It is common for workers to be required to wear protective gear such as helmets including a protective transparent or translucent face mask in addition to move conventional gear such as heavy gloves when performing jobs that may result in excessive heat, injurious light or flying sparks, particles and heavier objects. The transparent or translucent members used in such face masks must be made of materials strong enough and with a thickness dimension large enough to withstand heavy impacts without breaking or giving way. In some cases, such members must be capable of filtering out undesired portions of incident light.
In use, such transparent or translucent members are exposed to forces which tend to scratch or scrape the exterior surface thereof as well as to localized pitting or burning and the deposition of opaque materials thereon. In any event, after use over a period of time, the optical quality of such transparent or translucent members will tend to be impaired to an extent sufficient to produce a safety hazard.
It has been proposed in the prior art to mount the transparent or translucent members on the face mask or helmet structure in such a way as to facilitate removal and replacement of such members (see for example U.S. Pat. No. 2,186,817 issued to Fredrick M. Bowers on Jan. 9, 1940). However, the transparent or translucent members are not inexpensive and they tend to require appropriate storage in quantity other than at the job site. Furthermore, it is necessary to interrupt the job in progress and remove the helmet or face mask from use in order to replace the transparent or translucent member thereof. The end result is that such members are not replaced as soon as they should be and they can introduce a safety hazard due to impaired optical quality which is often as great as the safety hazard they are intended to overcome.
It is an object of this invention to provide a method of and means for shielding the exterior surface of the transparent or translucent members of a face mask structure against abrasion, pitting, burning and the deposition of opaque materials thereon.
It is another object of this invention to provide such a method and means which is simple and inexpensive.
It is a further object of this invention to provide such a method and means which will enable the optical qualities of the face mask to be maintained without interruption of a job in progress or removal of the face mask from service.
It has been proposed in the prior art to provide a lens cover in the nature of a thin sheet or film that can be easily and quickly stuck to the lens and which can likewise be easily and quickly removed. See for example U.S. Pat. No. 2,511,329 issued to Edward Craig on June 13, 1950, in which it is further proposed that the thin sheets be provided with an adhesive on one side thereof and arranged in a pack for carrying or handling and that the sheets can be removed from the pack and applied to the lens one at a time.
However, such sheets are difficult to separate from the pack one at a time, particularly while wearing working gloves. Furthermore, the pack is likely to be lost or mislaid and may not be available at the work site when needed. Finally, the presence of the adhesive across the surface of the lens cover tends to degrade the optical quality thereof and introduce the possibility that foreign matter will adhere thereto and further degrade optical quality.
Thus, it is yet another object of this invention to provide for the shielding of the exterior surface of the transparent member of a face mask by mounting a stack of thin flexible sheets of transparent or translucent material thereagainst for removal therefrom one at a time.
It is a still further object of this invention to provide a thin flexible sheet of transparent or translucent material which is particularly adapted for individual removal from a stack thereof using gloved hands.
It is yet a further object of this invention to provide such a thin flexible sheet which is particularly adapted to provide a visible indication of the fact that a second one thereof is in stacked relation thereto without detracting from the ease of individual removal thereof.